/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 1997-2007 Sun Microsystems, Inc.  Portions Copyrighted 2008 Richard Schilling.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
 * Sun designates this particular file as subject to the "Classpath" exception
 * as provided by Sun in the GPL Version 2 section of the License file that
 * accompanied this code.  If applicable, add the following below the License
 * Header, with the fields enclosed by brackets [] replaced by your own
 * identifying information: "Portions Copyrighted [year]
 * [name of copyright owner]"
 *
 * Contributor(s): Richard Schilling (coderroadie@gmail.com)
 *
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
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 */

package com.sun.mail.imap;

import java.util.Vector;

import javax.mail.*;

import com.sun.mail.util.*;
import com.sun.mail.imap.protocol.MessageSet;
import com.sun.mail.imap.protocol.UIDSet;

/**
 * Holder for some static utility methods.
 * 
 * @author John Mani
 * @author Bill Shannon
 */

public final class Utility {

    // Cannot be initialized
    private Utility() {}

    /**
     * Run thru the given array of messages, apply the given
     * Condition on each message and generate sets of contiguous
     * sequence-numbers for the successful messages. If a message
     * in the given array is found to be expunged, it is ignored.
     * ASSERT: Since this method uses and returns message sequence
     * numbers, you should use this method only when holding the
     * messageCacheLock.
     */
    public static MessageSet[] toMessageSet(Message[] msgs, Condition cond) {
        Vector v = new Vector(1);
        int current, next;

        IMAPMessage msg;
        for (int i = 0; i < msgs.length; i++) {
            msg = (IMAPMessage) msgs[i];
            if (msg.isExpunged()) // expunged message, skip it
                continue;

            current = msg.getSequenceNumber();
            // Apply the condition. If it fails, skip it.
            if ((cond != null) && !cond.test(msg))
                continue;

            MessageSet set = new MessageSet();
            set.start = current;

            // Look for contiguous sequence numbers
            for (++i; i < msgs.length; i++) {
                // get next message
                msg = (IMAPMessage) msgs[i];

                if (msg.isExpunged()) // expunged message, skip it
                    continue;
                next = msg.getSequenceNumber();

                // Does this message match our condition ?
                if ((cond != null) && !cond.test(msg))
                    continue;

                if (next == current + 1)
                    current = next;
                else { // break in sequence
                       // We need to reexamine this message at the top of
                       // the outer loop, so decrement 'i' to cancel the
                       // outer loop's autoincrement
                    i--;
                    break;
                }
            }
            set.end = current;
            v.addElement(set);
        }

        if (v.isEmpty()) // No valid messages
            return null;
        else {
            MessageSet[] sets = new MessageSet[v.size()];
            v.copyInto(sets);
            return sets;
        }
    }

    /**
     * Return UIDSets for the messages. Note that the UIDs
     * must have already been fetched for the messages.
     */
    public static UIDSet[] toUIDSet(Message[] msgs) {
        Vector v = new Vector(1);
        long current, next;

        IMAPMessage msg;
        for (int i = 0; i < msgs.length; i++) {
            msg = (IMAPMessage) msgs[i];
            if (msg.isExpunged()) // expunged message, skip it
                continue;

            current = msg.getUID();

            UIDSet set = new UIDSet();
            set.start = current;

            // Look for contiguous UIDs
            for (++i; i < msgs.length; i++) {
                // get next message
                msg = (IMAPMessage) msgs[i];

                if (msg.isExpunged()) // expunged message, skip it
                    continue;
                next = msg.getUID();

                if (next == current + 1)
                    current = next;
                else { // break in sequence
                       // We need to reexamine this message at the top of
                       // the outer loop, so decrement 'i' to cancel the
                       // outer loop's autoincrement
                    i--;
                    break;
                }
            }
            set.end = current;
            v.addElement(set);
        }

        if (v.isEmpty()) // No valid messages
            return null;
        else {
            UIDSet[] sets = new UIDSet[v.size()];
            v.copyInto(sets);
            return sets;
        }
    }

    /**
     * This interface defines the test to be executed in
     * <code>toMessageSet()</code>.
     */
    public static interface Condition {

        public boolean test(IMAPMessage message);
    }
}
